{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-21905", "assignerOrgId": "8cbe9d5a-a066-4c94-8978-4b15efeae968", "state": "PUBLISHED", "assignerShortName": "juniper", "dateReserved": "2026-01-05T17:32:48.710Z", "datePublished": "2026-01-15T20:19:22.158Z", "dateUpdated": "2026-01-16T16:26:02.071Z" }, "containers": { "cna": { "affected": [ { "defaultStatus": "unaffected", "platforms": [ "SRX Series", "MX Series with MX-SPC3", "MX Series with MS-MPC" ], "product": "Junos OS", "vendor": "Juniper Networks", "versions": [ { "lessThan": "21.2R3-S10", "status": "affected", "version": "0", "versionType": "semver" }, { "lessThan": "21.4R3-S12", "status": "affected", "version": "21.4", "versionType": "semver" }, { "lessThan": "22.4R3-S8", "status": "affected", "version": "22.4", "versionType": "semver" }, { "lessThan": "23.2R2-S5", "status": "affected", "version": "23.2", "versionType": "semver" }, { "lessThan": "23.4R2-S6", "status": "affected", "version": "23.4", "versionType": "semver" }, { "lessThan": "24.2R2-S3", "status": "affected", "version": "24.2", "versionType": "semver" }, { "lessThan": "24.4R2-S1", "status": "affected", "version": "24.4", "versionType": "semver" }, { "lessThan": "25.2R1-S1, 25.2R2", "status": "affected", "version": "25.2", "versionType": "semver" } ] } ], "configurations": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "The SIP ALG must be enabled to be vulnerable to this issue. The SIP ALG is enabled by default on MX-SPC3 and some SRX Series platforms. For other platforms, the following configuration is required:

\n\n[security alg sip enable]
\n
On SRX Series and MX Series with MX-SPC3, the SIP ALG status can be confirmed via the 'show security alg status' command:
\n
\nuser@junos> show security alg status
\nALG Status:
\n...
\n  SIP     : Enabled
" } ], "value": "The SIP ALG must be enabled to be vulnerable to this issue. The SIP ALG is enabled by default on MX-SPC3 and some SRX Series platforms. For other platforms, the following configuration is required:\n\n\n\n[security alg sip enable]\n\n\nOn SRX Series and MX Series with MX-SPC3, the SIP ALG status can be confirmed via the 'show security alg status' command:\n\n\n\nuser@junos> show security alg status\n\nALG Status:\n\n...\n\n  SIP     : Enabled" } ], "datePublic": "2026-01-14T17:00:00.000Z", "descriptions": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "A Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in the SIP application layer gateway (ALG) of Juniper Networks Junos OS on SRX Series and MX Series with MX-SPC3 or MS-MPC allows an unauthenticated network-based attacker sending specific SIP messages over TCP to crash the flow management process, leading to a Denial of Service (DoS).

On SRX Series, and MX Series with MX-SPC3 or MS-MPC service cards, receipt of multiple SIP messages causes the SIP headers to be parsed incorrectly, eventually causing a continuous loop and leading to a watchdog timer expiration, crashing the flowd process on SRX Series and MX Series with MX-SPC3, or mspmand process on MX Series with MS-MPC.

This issue only occurs over TCP. SIP messages sent over UDP cannot trigger this issue.

This issue affects Junos OS on SRX Series and MX Series with MX-SPC3 and MS-MPC:

" } ], "value": "A Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in the SIP application layer gateway (ALG) of Juniper Networks Junos OS on SRX Series and MX Series with MX-SPC3 or MS-MPC allows an unauthenticated network-based attacker sending specific SIP messages over TCP to crash the flow management process, leading to a Denial of Service (DoS).\n\nOn SRX Series, and MX Series with MX-SPC3 or MS-MPC service cards, receipt of multiple SIP messages causes the SIP headers to be parsed incorrectly, eventually causing a continuous loop and leading to a watchdog timer expiration, crashing the flowd process on SRX Series and MX Series with MX-SPC3, or mspmand process on MX Series with MS-MPC.\n\nThis issue only occurs over TCP. SIP messages sent over UDP cannot trigger this issue.\n\nThis issue affects Junos OS on SRX Series and MX Series with MX-SPC3 and MS-MPC:\n\n\n\n * all versions before 21.2R3-S10, \n * from 21.4 before 21.4R3-S12, \n * from 22.4 before 22.4R3-S8, \n * from 23.2 before 23.2R2-S5, \n * from 23.4 before 23.4R2-S6, \n * from 24.2 before 24.2R2-S3, \n * from 24.4 before 24.4R2-S1, \n * from 25.2 before 25.2R1-S1, 25.2R2." } ], "exploits": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "Juniper SIRT is not aware of any malicious exploitation of this vulnerability." } ], "value": "Juniper SIRT is not aware of any malicious exploitation of this vulnerability." } ], "metrics": [ { "cvssV3_1": { "attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1" }, "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ] }, { "cvssV4_0": { "Automatable": "YES", "Recovery": "AUTOMATIC", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "baseScore": 8.7, "baseSeverity": "HIGH", "privilegesRequired": "NONE", "providerUrgency": "AMBER", "subAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "CONCENTRATED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Amber", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "MODERATE" }, "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ] } ], "problemTypes": [ { "descriptions": [ { "cweId": "CWE-835", "description": "CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')", "lang": "en", "type": "CWE" } ] } ], "providerMetadata": { "orgId": "8cbe9d5a-a066-4c94-8978-4b15efeae968", "shortName": "juniper", "dateUpdated": "2026-01-15T20:19:22.158Z" }, "references": [ { "tags": [ "vendor-advisory" ], "url": "https://supportportal.juniper.net/JSA106004" }, { "tags": [ "vendor-advisory" ], "url": "https://kb.juniper.net/JSA106004" } ], "solutions": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "The following software releases have been updated to resolve this specific issue: 21.2R3-S10, 21.4R3-S12, 22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S1, 25.2R1-S1, 25.2R2, 25.4R1, and all subsequent releases." } ], "value": "The following software releases have been updated to resolve this specific issue: 21.2R3-S10, 21.4R3-S12, 22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S1, 25.2R1-S1, 25.2R2, 25.4R1, and all subsequent releases." } ], "source": { "advisory": "JSA106004", "defect": [ "1876029" ], "discovery": "USER" }, "title": "Junos OS: SRX Series, MX Series with MX-SPC3 or MS-MPC: Receipt of multiple specific SIP messages results in flow management process crash", "workarounds": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "Where practical, use a firewall filter to limit SIP traffic over TCP.

Alternately, if the SIP ALG is not required, it can be explicitly disabled on SRX Series and MX Series with MX-SPC3 via:

# set security alg sip disable

" } ], "value": "Where practical, use a firewall filter to limit SIP traffic over TCP.\n\nAlternately, if the SIP ALG is not required, it can be explicitly disabled on SRX Series and MX Series with MX-SPC3 via:\n\n# set security alg sip disable" } ], "x_generator": { "engine": "Vulnogram 0.1.0-dev" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-01-16T16:25:54.871316Z", "id": "CVE-2026-21905", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-01-16T16:26:02.071Z" } } ] } }